Reversible spherical organic water microtraps

Spherical water microtraps were prepared via a two steps process, which comprises the preparation of cross-linked poly(methacrylic acid) spheres by distillation–precipitation polymerization and the subsequent conversion of carboxylic groups to the corresponding sodium salts by treatment with aqueous sodium hydroxide solution. The influence of the cross-linker amount was investigated in order to achieve greater water absorption and a reversibility of the initial spheres after drying the formed hydrogel or washing with an excess of organic solvent. We achieved the highest water absorbency of about 70 times their weight occurring rapidly and unlimited times reversible after going through repeatable cycles of absorption and drying. This new material, called microtraps, was developed for its incorporation into multilayer anticorrosive coatings to prevent contact of water with metallic substrates.